Circuit breaker



CIRCUIT BREAKER Filed Aug. 17, 1936 -Fig.1.

Inventor: Kurt Koch,

ttorneg.

Patented May 17, 1938 v' UNITED STATES CIRCUIT BREAKER Kurt Koch, Eichwalde, near Berlin, Germany, assignor to General Electric Company, a corporation of New York Application August 17, 1936, Serial No. 96,491

in Germany August 21, 1935 I 8 Claims. (oi. zoo-as) My invention relates to circuit breakers, more particularly to current responsive, automatic release devices for multiple-pole circuit breakers,

and has for an object the provision of a simple,

6 reliable, and inexpensive device of this character. Multiple-pole automatic circuit breakers have heretofore been provided with slow-acting thermal release devices and with quick-acting electromagnetic release devices, all of the release de- 10 vices being arranged to operate a. common latching member in response to predetermined current conditions. Ordinarily, the latching member controls a heavily biased tripping member arranged to operate the circuit breaker to its 15 open-circuit position upon operation of the latch to a releasing position. v

Arrangements of this type are particularly suitable where the thermal release devices comprise bimetallic elements, since such bimetallic 2 elements ordinarily have a rather limited current capacity and are capable of exerting only a relatively small force. The interposition of a latching member and a tripping member has the drawback, however, that the releasing time of the 25 circuit breaker is considerably increased. Ac-

cordingly, under short-circuit current conditions,

the bimetallic elements may be damaged during 40 pole circuit breakers of this type, to provide means for simultaneously adjusting the time interval required for any one of the thermal elements to effect automatic operation of the circuit breaker. It has heretofore been proposed to 45 accomplish this by mounting each of the thermal elements on a separate support and by providing means for simultaneously adjusting all of the supports. Such an arrangement necessarily requires rather complicated supporting and adjusting means for the thermal elements, and accordingly, it is a further object of my invention to provide a simple and reliable thermal release device in which the time-current settings of all of the thermal elements may be simultaneously adjusted independently of the supporting means for the individual thermal elements.

In carrying out my invention in one form, I provide a circuit breaker having a plurality of switch members, operating means for simultane- 5 ously moving the switch members between open and closed circuit positions, including an insulated crossbar extending across at least two poles of the circuit breaker, and a normally latched tripping member arranged to be released upon a predetermined movement of any of the thermal elements to strike the crossbar a hammer blow, and operate the switch members to their open circuit positions. addition, electromagnetic means are provided for moving the crossbar to operate the-switch members to open circuit position substantially instantaneously upon the occurrence of short circuit conditions independently of the tripping member.

More specifically, the thermal release device comprises a plurality of independently operable thermal elements, a latch member movable from a latching to a releasing position, and adjusting mechanism including a plurality of arms respectively disposed in the paths of movement of the thermal elements for operating the latch member to its releasing position in response to a predetermined movement of any of the thermal elements. The adjustable mechanism includes means for simultaneously varying the relation of each of the arms to its associated thermal element so as to vary the amount which each thermal element must move to effect operation of the latch member, and vary the time-current settings of the thermal elements.

For a more complete understanding of my invention, reference should now be had to the drawing in which Fig. 1 is a fragmentary perspective view of a multiple-pole circuit breaker provided with an automatic release device embodying my invention; and Fig. 2 is a somewhat diagrammatic perspective view of a preferred form of adjustable thermal release device for use in connection with the circuit breaker shown in Fig. 1.

Referring now to the drawing, I have shown my invention as applied to a three-pole switch or circuit breaker l0, only the middle pole of the circuit breaker being completely shown, the outer poles being omitted in order to simplify the drawing. The fixed contact of the middle pole of the circuit breaker comprises an angular member II which may be rigidly secured, as for example by a screw l2, to a suitable base plate (not shown). Arranged in cooperating relation with the fixed contact H, is a movable contact I3 carried by a curved switch member M which is preferably somewhat resilient and which is pivotally supported on a pin l5 carried by a bracket l6 which may also be secured to the base plate.

Disposed adjacent the switch member I4, is a blow-out and releasing coil I'l connected in circuit with the contacts ll and I3 in any suitable manner, the core I8 of the coil l1 being provided at its opposite ends with suitably shaped magnetizable plates. As shown, these magnetizable plates include upwardly extending blow-out portions l9, outwardly extending portions 20 for attachment to the base plate, and downwardly extending portions 2| which form pole pieces for attracting a magnetizable armature 22, one end of which is pivotally mounted on the pin l5.

The operating mechanism for the switch member l4 comprises a plurality of locking levers 23,

24, and 25, one end of the lever 23 being connected to the switch member l4, as shown, and the lever 25 being pivotally mounted on a fixed pivot pin 26 which is carried by suitable supporting plates 21. It will be understood that the supporting plates 21 extend outwardly from the base plate and in order to simplify the drawing, only a portion of one of the supporting plates 21 is shown.

It will be understood of course that each of the poles of the circuit breaker is identical with the arrangement thus far described, and the operating mechanisms of all of the circuit breaker poles are connected together by a crossbar 28 which is formed of suitable insulating material. Preferably, the crossbar 28 and the locking levers 24 of each pole of the circuit breaker are molded from suitable insulating material to form a single unitary member. As shown, the middle pole of the circuit is provided with a suitable operating member 29 which is secured to the locking lever 24 and which may be manipulated to effect operation of the switch member l4 in a manner to be more fully described hereinafter.

Pivotally mounted on suitable pivot pins 30 carried by the frame plates 21, is a substantially U-shaped member 3| which serves as a support for one end of a tripping spring 32, the other end of which is connected to a tripping member 33 pivoted intermediate its ends on the pivot pin 26. In addition to its function as a support for the spring 32, the U-shaped member 3| serves as a resetting member for the tripping member 33 and is provided, as shown, with a resetting finger 34 extending inwardly from one leg thereof. As shown, the leg of the U-shaped member 3| which supports the resetting finger 34 is provided with an elongate slot 35 which permits pivotal movement of the U-shaped member 3| about the pivot pin 30 without interference from the fixed pivot pin 26, and the other leg of the U-shaped member 3| is provided with a slot 36 into which extends a pin 31 carried by the lower end of the locking lever 25.

The tripping member 33 is normally held in the position shown in the drawing by a latching member comprising a catch 38 supported intermediate the ends of a bar 39 which extends between a pair of spaced-apart arms 40 pivotally mounted on pins 4|, only one of the arms 4|) being shown in the drawing. Also supported by the pivoted arms 40 of the latch member is a shaft 42 which is provided with a plurality of extending arms 43, shown as eccentric cams, which are respectively disposed in the paths of movement of a plurality of-bimetallic thermal elements 44. It will be understood of course that the U-shaped bimetallic elements 44, which are shown somewhat diagrammatically, are fixedly mounted at their open ends, the free ends of the bimetallic elements being movable into engagement with the associated arms or cams 43 when the bimetallic elements are heated. Each of the elements 44 may of course be heated in accordance with the current flowing in the associated pole of the circuit breaker either by connecting the bimetallic element directly in circuit with the switch member M or by providing a separate heater in the well-known manner.

As will be understood by those skilled in the art, the time-current characteristicof each of the bimetallic elements depends not only upon the physical characteristics of the bimetallic elements but also upon the normal spacing of the free ends of the bimetallic elements relative to the associated arms 43. As will be more fully described in connection with Fig. 2, the time current characteristic of all of the bimetallic elements may be simultaneously adjusted by rotating the shaft 42 so as to vary the relation of the arms 43 relative to the bimetallic elements.

Upon the occurrence of predetermined current conditions, the bimetallic elements 44 will fiex, and the free ends of the elements will press upwardlyon the shaft 42 so as to rotate the arms 40 about the pivots 4| suiiiciently to withdraw the catch 38 from engagement with the tripping member 33. Accordingly, the tripping member 33 is rotated in a clockwise direction about the pivot 26 in accordance with the force exerted by the spring 32 so as to strike the crossbar 28 a hammer blow and move the locking levers 23, 24 and 25 through deadcenter position. As indicated above, the switch member I4 is somewhat resilient, and accordingly, as soon as the locking levers pass through the deadcenter position, the switch member M will move to its open-circuit position. If desired, special biasing springs may be provided for operating the switch members to open-circuit position when the locking levers pass through their deadcenter positions.

As the locking lever 25 moves in a counterclockwise direction about its pivot 26 during the switch-opening movement, the pin 31 carried thereby engages one side of the slot 36, and accordingly, the U-shaped member 3| is rotated in a counterclockwise direction about its pivot 30 so as to engage the resetting finger 34 with a cooperating shoulder 45 on the tripping member 33 and thereby return. the tripping member 33 to the normal latched position shown in the drawing.

As soon as the bimetallic elements 44 have cooled suificiently to permit the catch 38 on the latch member to return to its latching position, the circuit breaker may be reclosed by pressing inwardly on the operating member :29 so as to return the locking levers to the position shown in the drawing, a crosspiece 46 on the locking lever 23 being arranged for engagement by a projection 41 on the locking lever 24 to limit the movement of the locking levers during the closing operation. During this closing operation, it will of course be observed that the lever 25 is rotated in a counterclockwise direction about its pivot, and accordingly, the pin 31 carried by the lower end of the lever 25 engages the other side of the slot '36 to return the U-shaped member 3| to its normal position and thus restress the spring 32.

On the occurrence of short-circuit conditions, one or more of the magnetizable armatures 22,

one of which is provided for each pole of the circuit breaker, are attracted substantially instantaneously by the pole pieces II, the extending end of each armature being arranged to strike an extending portion of the adjacent locking lever 24. Thus the crossbar 28 is operated with a hammer blow so as to quickly move. ali'of the locking levers through their deadcenter positions and eflect opening movement of the switch members it. Thus it will beseen that under short-circuit current conditions, the switch members are operated to their open-circuit positions substantially instantaneously and independently of the tripping member 33.

If desired, the circuit breaker may of course be opened manually by moving the operating member 29 outwardly, and in some cases, it may be desirable to provide a separate operating member for manually opening the circuit breaker. This may be accomplished by mounting the switchopening operating member on the lower end of a lever pivoted intermediate its ends on the pivot pin 26, the upper end of the lever being arranged to engage the crossbar 28. This additional operating member is omitted from the drawing for purposes of simplification.

The arrangement described above, by means of which the tripping member is returned to its its open-circuit position, since the opening movement of the switch member l4 thus occurs without opposition from the spring 32.

Referring now to Fig. 2, l; have shown a preferred form of thermal release device for providing simultaneous adjustment of all of the'poles oi the circuit breaker. In the embodiment. here shown, the latch member comprises apair of pivotally mounted arms 48 connected together by a shaft 48 which supports a suitable catch 88, and a rotatable shaft 5| journaled in the arms 48 is provided with a plurality of extending arms or eccentric cams 52 similar to the cams 48 shown in Fig. 1. As shown, each of the arms 821s disposed in the path of movement of one of the bimetallic therm'al elements 53, shown somewhat diagrammatically, and it will be apparent that the operative relation of thebimetallic elements 83 to the pivoted arms 48 may be adjusted simply by rotating the shaft II to vary the-relation of the eccentric arms 82 relative to the elements 88. Preferably, the shaft 8! and the anns 88 comprise a single member formed from suitable insulating material and in order to indicate the adjustment of the shaft 5|, one end of the shaft is provided with an indicating disk 84, one face of which is provided with suitable indicia 88. As

shown, the adjusting arm 48 is provided with a pointer 88, and in order to retain the shaft II in any desired position, a leaf spring 81 is provided, one end of which is supported on the strap 48 and the other end of which frictionally engages the periphery of the disk 54.

It will thus be seen that I have provided a simple adjusting means for simultaneously adjusting the time-current settings of a plurality of poles without varying either the normal position of the bimetallic elements 83 or the normal position of the latch member.

while I have shown a particular embodiment of my invention, it will be understood, of course, thatldonotwishtobelimitedtheretmlince many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A thermal release device comprising a pin rality of independently movable thermal elements, a latch member movable from a latching to a releasing position, mechanism including a plurality of cams respectively disposed in the paths of movement of said thermal elements for operating said latch member to said releasing position in response to a predetermined move- I ment of any of said thermal elements, and means for adjusting said mechanism to vary simultaneously the relation of each of said cams to its associated thermal element.

2. A thermal release device comprising a p1urality of independently movable thermal elements, a latch member movable from a latching to a releasing position, mechanism carried by said latch member including a plurality of extending cams respectively disposed in the paths of move ment of said thermal elements for operating said latch member to said releasing position in response to a predetermined movement of any of said thermal elements, and means for adjusting said mechanism to vary simultaneously the rela tion of each of said cams to its associated thermal element, whereby the time-current settings 0:? said thermal elements are simultaneously varied.

3. A thermal release device comprising a pinrality of independently movable thermal elements, a latch member movable from a latching to a releasing position, mechanism including a plurality of extending cams respectively disposed in the paths of movement of said thermal elements for operating said latch member to said releasing position in response to a predetermined movement of any of said thermal elements and means for rotating said mechanism relative to said latch member to vary simultaneously the spaced relation of each ofsaid cams to its associated thermal element. a

4. A thermal release device comprising a plurality of independently movable thermal elements, a latch member movable from a latching to a releasing position, mechanism including a plurality of interconnected cams respectively disposed in the paths of movement of said thermal elements for operating said latch member to said releasing position in response to a predetermined movement of any of said thermal elements, and means for simultaneously rotating said cams relative to said latch member to vary simultaneously the relatlon of each of said cams to its associated thermal element.

5. A thermal release device comprising a plurality of independently movable thermal elements, a latch member mounted for pivotal movement between latching and releasing positions, a shaft carried by said latch member having a plurality of eccentrics respectively disposed in the paths of movement of said thermal elements for engagement by said thermal elements to operate said latch member about its pivot to said releasing position in response to a predetermined movement of any of said thermal elements, and means for rotating said shaft to adjust said eccentrics simultaneously with relation to said ther- 'mal elements, whereby the time-current settings of said thermal elements are simultaneously varied.

6. A multipole circuit breaker comprising a plurality of switch members, operating means for said switch members including an insulated crossbar extending across at least two poles of said circuit breaker, a tripping member biased for movement in one direction, latch means normally restraining said tripping member, a plurality of independently operable thermal elements respectively associated with said switch members for operating said latch means to release said trip ping member upon the occurrence of predetermined current conditions, said tripping member being arranged to strike said crossbar a hammer blow to efiect simultaneous operation of said switch members to an open circuit position, and electromagnetic means for moving said crossbar to operate said switch members to said open circuit position independently of said tripping member upon the occurrence of other predetermined current conditions.

7. A multipole circuit breaker comprising a plurality of switch members, operating means for said switch members including an insulated crossbar extending across at least two poles of said circuit breaker; a tripping member biased for movement in one direction, latch means normally restraining said tripping member, a plurality of independently operable thermal elements respectively associated with said switch members for operating said latch means to release said tripping member upon the occurence of predetermined current conditions, said tripping member being arranged to strike said crossbar a hammer blow to effect simultaneous operation of said switch members to an open circuit position, and electromagnetic means associated with each of said switch members for striking said crossbar a hammer blow to effect simultaneous operation of said switch members to said open circuit position independently of said tripping member upon the occurrence of other predetermined current conditions.

8. A multipole circuit breaker comprising a plurality of switch members, operating means including a separate operating mechanism for each switch member, an insulated cross bar interconnecting said operating mechanisms for simultaneous operation between open and closed circuit positions, a tripping member biased for movement in one direction, latch means normally restraining said tripping member and operable to release said tripping member for movement to strike said crossbar a hammer blow, a plurality of independently operable thermal elements movable in response to predetermined currents in the respective switch members, mechanism engageable by any of said thermal elements for operating said latch means to releasing position in response to a predetermined movement of any of said thermal elements whereby simultaneous operation of said switch members to said open circuit position is effected, means for adjusting said mechanism relative to said thermal elements to vary simultaneously the time-current settings of said thermal elements, and electro-magnetic means associated with each switch member for moving said crossbar instantaneously to operate said switch members to said open circuit position independently of said tripping member upon the occurrence of short-circuit conditions.

KURT KOCH. 

